P-045 - Efficacy of Organic Fungicides on Foliar Diseases of Corn

A field trial was conducted in Princeton, Kentucky in 2024 to analyze the efficacy of organic fungicides for common foliar diseases of corn (Zea mays L.). The field trial consisted of five treatments with four replications per treatment in a randomized complete block design, for a total of twenty field plots. Each plot consisted of four rows and measured 3.05m wide by 9.14m long. Organic fungicides Bacillus amyloliquefaciens strain MBI 600, copper oxychloride + copper hydroxide, and hydrogen peroxide + peroxyacetic acid were compared to a synthetic fungicide of azoxystrobin + propiconazole + pydiflumetofen. A non-treated control was also included. All products were applied at labeled rates at corn growth stage VT/R1 (tassel/silk). Foliar disease severity ratings occurred at R5 (dent) for gray leaf spot (Cercospora zeae-maydis), southern rust (Puccinia polysora), and Curvularia leaf spot (Curvularia lunata). Severity ratings were analyzed in SAS using PROC GLIMMIX. Organic fungicides did not reduce any foliar diseases, compared to the non-treated control. In fact, plots that received hydrogen peroxide + peroxyacetic acid had higher levels of southern rust compared to all other treatments (P=0.0048). Azoxystrobin + propiconazole + pydiflumetofen reduced gray leaf spot severity compared to other products (P< 0.0001), indicating that organic fungicides applied once, at VT/R1, may not consistently reduce the diseases observed in this trial compared to a synthetic fungicide.